Re: [PATCH 1/2] phy: usb: Fix potential NULL dereference in sp_usb_phy_probe()

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Sep 09, 2022 at 09:35:45AM +0800, Sun Ke wrote:
> platform_get_resource_byname() may fail and return NULL, so we should
> better check it s return value to avoid a NULL pointer dereference
> a bit later in the code.
> 
> Fixes: 99d9ccd97385 ("phy: usb: Add USB2.0 phy driver for Sunplus SP7021")
> Signed-off-by: Sun Ke <sunke32@huawei.com>
> ---
>  drivers/phy/sunplus/phy-sunplus-usb2.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/phy/sunplus/phy-sunplus-usb2.c b/drivers/phy/sunplus/phy-sunplus-usb2.c
> index 5269968b3060..d73a8a421d9c 100644
> --- a/drivers/phy/sunplus/phy-sunplus-usb2.c
> +++ b/drivers/phy/sunplus/phy-sunplus-usb2.c
> @@ -249,11 +249,15 @@ static int sp_usb_phy_probe(struct platform_device *pdev)
>  	usbphy->dev = &pdev->dev;
>  
>  	usbphy->phy_res_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM, "phy");

How can this fail on this system?

> +	if (!usbphy->phy_res_mem)
> +		return -EINVAL;
>  	usbphy->phy_regs = devm_ioremap_resource(&pdev->dev, usbphy->phy_res_mem);
>  	if (IS_ERR(usbphy->phy_regs))
>  		return PTR_ERR(usbphy->phy_regs);
>  
>  	usbphy->moon4_res_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM, "moon4");

Same here, how can this fail?
Have you seen these failures happen in real systems?

thanks,

greg k-h